Genetic variability and heritability among durum wheat (Triticum durum Desf.) lines for grain yield and its components performance

Durum wheat (Triticum durum Desf.) is a staple crop in Tunisia and the Mediterranean region, where yield is strongly influenced by environmental variability. The present study evaluated 19 durum wheat lines over two cropping seasons (2021–2022 and 2022–2023) to assess genetic variability, heritability, and expected genetic advance for grain yield and its components. Variance analysis revealed significant effects of genotype, year and their interaction on most traits. Environmental conditions accounted for the largest proportion of variation in grain yield (77.91%), highlighting the dominant influence of year-to-year climatic differences. Significant genotypic variation was observed for number of plants per square meter, number of spikes per square meter, number of grains per spike, thousand-kernel weight, and grain yield, identifying promising lines for further selection. A high broad-sense heritability  for the number of grains per spike (83.04%) with a corresponding expected genetic gain of 9.18, indicating strong additive genetic control and potential for effective selection. Other traits exhibited lower heritability and genetic gains, reflecting a substantial environmental influence. These findings provide valuable information for durum wheat breeding programs aimed at enhancing grain yield and stress adaptation in Tunisia and similar environments.